I am going to guess to Excursion sits at a different hieght, and thus your hitch was a little off camber with the F250. The Equalizer is a good hitch, but it is definitely picky about setup. I was amazed at the difference 1 washer made when I had mine. The attitude of the truck was hardly different when sitting empty (less than 1/4" change), but towing was different experience (much better in that case). I also noticed if I made big changes to the load in the bed of the pickup, I would notice a change in how the trailer towed.
FWIW, there is a Propride 3P for sale on this site. I saw it when I was looking for the sign guy. Pricing looked decent, shipping might kill the deal though.
Current TV:'14 F350 Lariat CrewCab, 4x4 Short Bed SRW Diesel w/ Pullrite 2700 (16K)
Current Fiver: '15 Puma 295BHSS Anniversary Edition
Past TV: '13 F150 HD Payload SCrew EB, '08 Tundra CrewMax 5.7L, '02 'Burb 5.3L, '97 Dakota 3.9L
Past Trailers: '09 Wildwood LE 27RB, '02 Palomino Yearling RL, '87 Jayco 1006dlx